Methods and devices for automated biopsy and collection of soft tissue

ABSTRACT

Instruments for performing percutaneous biopsy procedures are disclosed, which have advantageous features for improving functionality and performance over prior art devices. These instruments comprise two types, single-use devices, and multiple-use devices having active tissue capture capability. Improved features include the ability to retrieve and evaluate multiple tissue samples during a single insertion procedure, without physical handling of the samples, as well as constructional features, such as a molded tissue cassette housing, variant vacuum port embodiments suited for different tissue environments, and a method for backflushing the instrument to remove biological debris, among others.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of co-pending parentapplication Ser. No. 08/217,246, filed Mar. 24, 1994.

FIELD OF THE INVENTION

[0002] The present invention relates to methods and devices for tissuesampling, and more specifically to improved biopsy instruments andmethods for acquiring subcutaneous biopsies and for removing lesions.

BACKGROUND OF THE INVENTION

[0003] It is often desirable and frequently necessary to sample or testa portior tissue from humans and other animals, particularly in thediagnosis and treatment of patients with cancerous tumor, pre-malignantconditions, and other diseases or disorders. Typically, in the case ofcancer, when the physician establishes by means of procedures such aspalpation, x-ray, or ultrasound imaging that suspicious circumstancesexist, a biopsy is performed to determine whether the cells arecancerous. Biopsy may be done by an open or percutaneous technique. Openbiopsy, which is an invasive surgical procedure using a scalpel andinvolving direct vision of the target area, removes the entire mass(excisional biopsy) or a part of the mass (incisional biopsy).Percutaneous biopsy, on the other hand, is usually done with aneedle-like instrument through a relatively small incision, blindly orwith the aid of an artificial imaging device, and may be either a fineneedle aspiration (FNA) or a core biopsy. In FNA biopsy, individualcells or clusters of cells are obtained for cytologic examination andmay be prepared such as in a Papanicolaou smear. In core biopsy, as theterm suggests, a core or fragment of tissue is obtained for histologicexamination which may be done via a frozen section or paraffin section.

[0004] The type of biopsy utilized depends in large part oncircumstances present with respect to the patient, and no singleprocedure is ideal for all cases. However, core biopsy is extremelyuseful in a number of conditions and is being used more frequently bythe medical profession.

[0005] Two types of image guided percutaneous core breast biopsyinstruments are presently available. One such instrument is aspring-powered single-use device, such as the BIOPTY® gun, availablefrom C.R. Bard, Inc. Such a gun is shown and described in U.S. Pat. Nos.4,699,154 and 4,944,308, as well as in U.S. Reissued Pat. No. Re.34,056, all of which are herein expressly incorporated by reference.These devices are useful because of their inexpensive construction,enabling them to be economically used for only a single patient, andbecause they are lightweight and easy to use. However, they also havedisadvantages. An important disadvantage is that the small core sizemakes it necessary to accurately place the needle when sampling smalllesions. To sample a lesion thoroughly, many separate insertions must bemade. Each time a new sample is taken, the device must be removed, andthe breast or organ must be punctured again upon reinsertion of thedevice. This action is tedious and time consuming.

[0006] A further disadvantage of such single-use guns is the needletypically used in such a device, e.g. the True Cut® needle manufacturedby Travenol Laboratories. This needle optimally allows a roughlycylindrical shaped sample of tissue, termed a “core”, to be obtainedfrom a pointed, side cutting device, percutaneously, and comprises apointed inner stilette with a side-facing notch to receive tissue nearits distal pointed end and an outer, sharpened sliding cannula. Inoperation, once the lesion is targeted the inner stilette is thrust intothe organ or lesion of interest. Tissue passively prolapses into theside facing notch and the outer cannula is rapidly advanced, therebysevering the sample of tissue contained within the notch. Unfortunately,the True Cut® needle is rough on organs and lesions, often onlyobtaining small fragments of tissue, and is quite operatordependent—some individuals are good at operating the device and some arenot. It also is tissue selective, meaning that the piercing stilette andsliding cutter can “push away” the lesion of interest, particularly insituations where a relatively large lesion is surrounded by much softertissue (i.e. fat).

[0007] The second type of image guided percutaneous core breast biopsyinstrument currently available is a vacuum-assisted automatic corebiopsy device. One such successful biopsy gun is shown and disclosed inrelated parent application Ser. No. 08/217,246, filed on Mar. 24, 1994,which is commonly owned by the assignee of the present application andis herein incorporated by reference. This gun has the capability toactive capture tissue prior to cutting the tissue. Active capture allowsfor sampling through non-homogeneous tissues, meaning that the device isequally capable of cutting through hard and soft tissue. The gun alsoincludes means to direct and position the cutting chamber in arbitrarypositions about and along its longitudinal axis, means for rapid andatraumatic removal of an arbitrary number of core samples with only asingle needle insertion into the body and organ, and means for codingand decoding the location from which the samples were obtained.Together, these capabilities allow for more complete sampling of largelesions and for the complete removal of small lesions. This type ofinstrument has been very successful in permitting the obtainment of aplurality of tissue samples from different locations with only a singleneedle insertion, as well as in obtaining high quality samples in amanner which does not require direct handling of the samples by theoperator. However, it does not operate equally well in all proceduresand in all bodily environments. For example, instrument performance andsuccess often varies dependent upon the type of body tissue beingsampled; i.e. relatively fatty or relatively hard.

[0008] What is needed then, are innovations for improving the qualityand completeness of the tissue sample obtained using a single-use corebiopsy instrument, as well as constructional improvements and variantswith respect to the active capture type of instrument which will permitit to operate with maximum efficiency and to operate equally well in alltissue environments.

SUMMARY OF THE INVENTION

[0009] This invention addresses the aforementioned needs by providing anumber of important new features and innovations for-the active capturetype of biopsy instrument which each collectively or singly contributeto improved and more versatile operation. For example, such innovationsinclude a molded tissue cassette housing, permitting easy andinexpensive fabrication while also permitting the handling and viewingof multiple tissue samples without physical contact by the instrumentoperator. The housing is interconnected with the piercing needle using athumbwheel which permits the needle-to rotate relative to the housingthereby preventing the vacuum tube from wrapping about the housing.Several variant vacuum port embodiments are disclosed, each of whichhave advantages in certain tissue environments. Also disclosed is amethod for backflushing biological debris from the instrument whichbuilds up after repeated sampling procedures, without removing theinstrument from the selected tissue location.

[0010] With respect to the single-use type of biopsy instrument, severaltissue capture embodiments are disclosed for improving the captureprocess, so that complete and well preserved samples are obtained. Manyof these embodiments are also applicable for use with the active captureinstrument type.

[0011] More particularly, in one aspect of the invention, a biopsyinstrument is provided which comprises a housing and a needle assembly,wherein the needle assembly includes a tubular piercing member having adistal pointed end and a laterally positioned tissue receiving portproximate to the distal pointed end which opens into a tissue samplechamber. The tubular piercing member is rotatably attached to thehousing and held in an axially fixed position within a selected tissuemass. The needle assembly further includes a cannular cutting memberadapted to coact with the tubular piercing member to cut a tissue samplefrom the tissue mass. The tissue sample is transported to a proximateend of the tubular piercing member by the cutting member as it iswithdrawn proximally along the tubular piercing member. An elongateknock-out pin is disposed coaxially within the tubular piercing memberand the cannular cutting member for the primarily purpose of dislodgingthe tissue sample from the cutting member at a predetermined location asthe cutting member is withdrawn.

[0012] Surprisingly, the inventors have found that preferably, in orderto mining tissue clogging of the cutter, the knock-out pin should havean effective diameter or cross-sectional area of at least 0.030 inches,and the ratio of the effective diameter of the knock-out pin to theinternal diameter of the cannular cutter should be at leastapproximately one-half.

[0013] In another aspect of the invention, a biopsy instrument includesan elongate hollow outer piercing needle having a lumen, a sharpeneddistal end for piercing tissue, and a lateral opening located proximalto the sharpened distal end for receiving a portion of a tissue masspositioned adjacent to the lateral opening. Also included are anelongate inner cutting cannula having a lumen, which is disposedcoaxially and slidably within the outer piercing needle. The innercannula has a sharpened distal end for cutting the portion of tissueprotruding into the lateral opening of the outer piercing needle whenthe inner cannula slides distally past the lateral opening. This causesthe portion of cut tissue to be deposited within the inner cannulaproximal to the distal end. A vacuum generator generates a vacuumpressure which fluidly communicates with the lateral opening through theinner cannula lumen. In such an embodiment, it is often desirable toprevent the tissue sample from migrating proximally through the cuttingcannula lumen, so an inventive tissue stop device is disposed in thelumen of the inner cannula which has a structure, preferably a corkscrewportion of a linear wire, disposed proximally of the lateral opening.This structure sufficiently obstructs the lumen so that the tissuesample cannot migrate proximally past it.

[0014] In yet another aspect of the invention, a biopsy instrumentincludes an outer hollow cannula living a distal end portion whichcomprises a plurality of leaftlets. Each leaflet has a proximal endwhich is hinged to the outer cannula wall and a distal end, and are eachbiased to pivot about their hinges to a closed position wherein thedistal ends of the leaflets contact one another. The instrument furtherincludes an inner hollow cannula, and at least one of the inner andouter cannulas is slidable relative to the other cannula, so that firstthe inner cannula may be extended distally with respect to the outercannula to force the leaflets to an open position, and to cut andcontain a tissue sample, and then the outer cannula may be extendeddistally with respect to the inner cannula sufficiently so that theleaflets clear the inner cannula and snap closed about their hinges,thereby severing the tissue sample and containing it within the innercannula.

[0015] In a further aspect of the invention, a biopsy instrument has anouter hollow cannula having a sharpened distal end portion and an innerhollow cannula having a distal portion which is biased to expandradially at its distal end. At least one of the cannulas is slidablerelative to the other cannula, so that first the inner cannula may beextended distally with respect to the outer cannula, such that the innercannula distal portion expands radially to capture a tissue sample. Thenthe outer cannula may be extended distally with respect to the innercannula sufficiently so that the distal end portion of the inner cannulais forced by the outer cannula to close about and sever the tissuesample, thereby containing the sample within the inner cannula. Thedistal portion of the inner cannula may comprise, for example, either analligator tip having a pair of hinged jaws which are biased to expandradially, or a plurality of hooked extractors.

[0016] Still another aspect of the invention involves a method forflushing debris form a biopsy instrument, which includes an outerpiercing needle having a laterally positioned tissue receiving portwhich opens into a tissue receiving chamber and an inner cutting cannulahaving an axial lumen and a sharpened distal end, which is disposedcoaxially and slidably within the outer piercing needle. Furtherincluded in the biopsy instrument is a vacuum lumen disposed beneath thetissue receiving port which further comprises at least one fluidcommunication port disposed distally of the distal end of the innercannula when the inner cannula is in its fully advanced position. Theinventive method includes the steps of advancing the inner cannula ofthe instrument so that it extends distally sufficiently to completelyclose off the tissue receiving port and then injecting a pressurizedfluid through one of the inner cannula and the vacuum lumens, so thatthe fluid flows through the fluid communication port and into the otherone of the two lumens, from which the fluid returns to its source,thereby flushing accumulated debris from the biopsy instrument.

[0017] The invention, together with additional features and advantagesthereof, may best be understood by reference to the followingdescription taken in conjunction with the accompanying illustrativedrawing.

BRIEF DESCRIPTION OF THE DRAWING

[0018]FIG. 1 is a perspective view of an automatic core biopsy device ofthe type shown and described in co-pending patent application Ser. No.08/217,246;

[0019]FIG. 2 is a schematic plan view, from the left side, of a portionof the needle assembly of the device illustrated in FIG. 1, showing thedevice before it penetrates a target lesion;

[0020]FIG. 3 is a schematic plan view similar to FIG. 2, showing thedevice after it has penetrated the target lesion, in a position to begincollecting tissue samples;

[0021]FIG. 4 is a cross-sectional view, from the left side, of theneedle assembly of the device illustrated in FIG. 1;

[0022]FIG. 5 is an enlarged perspective view of the portion of FIG. 1delineated by the numeral 5.

[0023]FIG. 6 is a cross-sectional view of one embodiment of the needleassembly illustrated in FIG. 5;

[0024] FIG.7 is a cross-sectional view taken along lines 7-7 of FIG. 6;

[0025]FIG. 8 is ad enlarged cross-sectional view taken along lines 8-8of FIG. 3;

[0026]FIG. 9 is an enlarged cross-sectional view similar to FIG. 8,illustrating the withdrawal of the cutter after insertion of the needleinto the target lesion;

[0027]FIG. 10 is an enlarged cross-sectional view similar to FIG. 8,illustrating the prolapse of tissue into the tissue receiving portfollowing the application of the vacuum pressure;

[0028]FIG. 11 is an enlarged cross-sectional view similar to FIG. 8,illustrating the simultaneous rotation and distal advancement of the cutto cut off a tissue sample;

[0029]FIG. 12 is an enlarged cross-sectional view similar to FIG. 8,illustrating the proximal withdrawal of the cutter with the tissuesample contained therein;

[0030]FIG. 13 is an enlarged cross-sectional view of the interfacebetween the proximal end of the tissue cassette and the tissue cassettehousing illustrated in FIG. 4, showing the operation of the, knock-outpin to retain the tissue sample in the tissue cassette as the cutter iswithdrawn proximally;

[0031]FIG. 14 is a cross-sectional view taken along lines 14-14 of FIG.10;

[0032]FIG. 15 is a cross-sectional view taken along lines 15-15 of FIG.12;

[0033]FIG. 16 is a cross-sectional view similar to FIG. 14, wherein theouter needle and inner cutter have been rotated approximately 90 degreescounterclockwise to take a second tissue sample;

[0034]FIG. 17 is a cross-sectional view similar to FIG. 15, wherein theouter needle and inner cutter have been rotated approximately 300degrees counterclockwise, and a fourth tissue sample has been taken;

[0035]FIG. 18 is a cross-sectional view of a second embodiment of theneedle assembly shown in FIG. 3;

[0036]FIG. 19 is a cross-sectional view along lines 19-19 of FIG. 18;

[0037]FIG. 20 is a cross-sectional view of a third embodiment of theneedle assembly shown in FIG. 3;

[0038]FIG. 21 is a top plan schematic view of the tissue receiving portof a fourth modified needle assembly embodiment;

[0039]FIG. 22 is a cross-sectional view similar to FIG. 3, illustratinga fifth modified needle assembly embodiment;

[0040]FIG. 23 is a cross-sectional view through the tissue port of aneedle assembly like that shown in FIG. 5, illustrating a potentialtissue binding situation under certain operating regimes;

[0041]FIG. 24 is a fragmentary cross-sectional view of the cuter portionof a sixth modified needle assembly embodiment, illustrating aninventive solution to prevent potential tissue binding situations likethat illustrated in FIG. 23;

[0042]FIG. 25 is a cross-sectional view of a prior art single-use biopsydevice, of the type shown and described in U.S. Pat. No. 4,699,154;

[0043]FIG. 26 is a fragmentary cross-sectional view of a modified needleassembly for a biopsy gun of the type illustrated in FIG. 25,illustrating the needle assembly in a first position for advancing theneedle assembly through tissue to a selected tissue sample site;

[0044]FIG. 27 is a fragmentary cross-sectional view of the needleassembly illustrated in FIG. 26, showing the needle assembly in a secondposition for obtaining and cutting a tissue sample;

[0045]FIG. 28 is a fragmentary cross-sectional view of the needleassembly illustrated in FIG. 26, showing the needle assembly in a thirdposition wherein the tissue sample has been severed and is contained inthe tissue receiving port of the needle assembly;

[0046]FIG. 29 is a fragmentary cross-sectional view of a second modifiedneedle assembly for a biopsy gun of the type illustrated in FIG. 25,illustrating the needle assembly in a first position for advancementinto the selected tissue sample site;

[0047]FIG. 30 is a fragmentary cross-sectional view of the needleassembly illustrated in FIG. 29, showing the needle assembly in a secondposition after capture of a tissue sample;

[0048]FIG. 31 is a schematic exploded view of a third modified needleassembly for a biopsy gun of the type illustrated in FIG. 25;

[0049]FIG. 32 is a schematic side elevational view of the needleassembly illustrated in FIG. 31, showing the assembly in a firstposition approaching a selected tissue sample;

[0050]FIG. 33 is a schematic side elevational view similar to FIG. 32,illustrating the needle assembly in a second position grabbing theselected tissue sample; and

[0051]FIG. 34 is a schematic side elevational view similar to FIG. 32,illustrating the needle assembly in a third position after capture ofthe selected tissue sample.

DESCRIPTION OF THE INVENTION

[0052] Referring now to FIGS. 1, 4, and 5, a preferred embodiment of anautomatic core biopsy device 10 of the type disclosed in related patentapplication Ser. No. 08/217,246 is illustrated. The illustrated biopsyinstrument 10 comprises a housing 14 having a hinged lid 16. A needleassembly 18 extends out of the housing 14, and comprises a hollow outerpiercing needle 20, an inner cuter 22 having a lumen 23 (FIG. 5), atissue cassette housing 24, and a tissue cassette 26. The hollow outerpiercing needle 20 further includes a tissue receiving port or bowl 28.A thumbwheel 30 interconnects the tissue cassette housing 24 and thehollow outer piercing needle 20, preferably permitting rotation of theneedle 20 without rotating the tissue cassette housing 24, as will bemore completely described hereinbelow. A vacuum port 32 in the tissuecassette housing 24 is adapted for attachment to a vacuum source througha tube or tubing 34, in order to provide a vacuum at the tissuereceiving port or bowl 28. Preferably, the vacuum is supplied through aseparate vacuum lumen 35, but may alternatively or simultaneously besupplied directly through the lumens of the hollow outer piercing needle20 and the inner cutter 22, respectively, if desired.

[0053] Telescopically and coaxially arranged within the hollow outerpiercing needle 20 and the inner cutter 22 is a knock-out pin 36. It ismounted to be stationary, and is preferably fabricated of stainlesssteel, but may also be constructed of other biocompatible materials,such as plastic. The pin 36 preferably is tubular, and the hub H of theknock-out pin serves as a secondary vacuum port which supplies thevacuum through the needle 20 and inner cutter 22. Surprisingly,Applicants have found that it is important to appropriately size theknock-out pin to mini e clogging problems. For this reason, it has beenfound that, for the preferred embodiment where the inner diameter of theouter piercing needle 20 is approximately 0.074 inches and the innerdiameter of the inner cute 22 is approximately 0.063 inches, theeffective diameter of the knock-out tube 36, meaning the cross-sectionalarea of the tube, should be at least approximately 0.030 inches.Preferably, the effective diameter of the knock-out tube is about 0.045inches.

[0054] The biopsy instrument housing 14 contains the driving mechanismsand controls for operating the needle assembly 18, and may be mounted ina stationary fashion on a base 37. This base 37 may be an integral partof the housing 14 and is preferably designed to mate with an I-beam railof a stereotactic imaging unit, but may be modified and designed tomatch and mate with any of the various imaging units available in theindustry. The driving mechanisms for the illustrated preferredembodiment include a long spur gear 38 and a cutter drive gear 40, whichis housed within a pinion housing 42 and is rotatably and drivinglyattached to the inner cutter 22 within the housing 14. In order torotate or oscillate the cutter 22, the gear 38 is rotated by a drivingmotor or stepper motor (not shown). Rotation or oscillation of the gear38 in turn drives the gear 40 to rotate or oscillate, thereby rotatingor oscillating the cutter 22.

[0055] In addition to rotation or oscillation, the cutter 22 may also bedriven to travel axially; both distally and proximally. A slide handle44, which is attached along with the pinion housing 42 to a slide (notshown), may be actuated by an operator in either direction, asillustrated by the arrow 46, to drive the pinion housing 42 axially.Since the cutter 22 is fixedly attached to the pinion gear 40, which inturn is contained within the pinion housing 42, the cutter follows theaxial travel of the pinion housing, permitting the operator to advanceor ret the cutter, as desired.

[0056] A piercing mechanism or linear actuator 47, located distally of apartition 48 in the housing 14, functions to rapidly advance the entireneedle assembly 18 distal in order to locate the tip of the outerpiercing needle 20 at the site from which one or more tissue samples aredesired. The piercing mechanism preferably includes a driving spring(not shown), a carriage assembly 50, which is attached to a proximal endportion 52 of the tissue cassette housing 24, a cocking lever 54 whichoperates against a fixed lever 55, a pierce button 56, and a safetybutton 57. Operation of the piercing mechanism is described in greaterdetail hereinbelow.

[0057] Of course, the illustrated embodiment is just one of manypossible ways to drive and control an automatic core biopsy device ofthe type shown and described. For example, the control system could bean integral part of the computer system in the stereotactic or otherimaging device used to guide the biopsy device, so that the stereotacticdevice computer would be used to control the cutter, the angular andlongitudinal position of the piercing needle 20, and the knockout tubeposition. Additionally, different driving mechanisms could be employed,such as substituting a friction drive for the long spur gear drive. Insome instances it may be preferred to be able to rotatably and linearlydrive and control the hollow outer piercing needle and the knock-outpin, as well as the inner cutter, as disclosed in co-pending applicationSer. No. 08/217,246, or to employ one of the other needle assembly orneedle assembly driving arrangement embodiments disclosed therein. Ofcourse, any of the embodiments disclosed in that application may also beused in conjunction with the inventions herein disclosed.

[0058] In operation, as described in the aforementioned co-pendingapplication and with particular reference to FIGS. 2,3, and 8 through13, in addition to FIGS. 1, 4, and 5, the point 58 of the needle 20 isfirst moved into position to pierce the lesion or selected tissue whichis to be sampled (FIGS. 2 and 3). The initial global position of thepoint 58 with respect to the tissue area being sampled is determined bythe overall position of the biopsy instrument 10 with respect to thepatient For example, the biopsy instrument 10 may be mounted on acommercially available stereotactic guidance system (not shown),commonly used in the medical field for accurate positioning of a varietyof medical devices with respect to a patient and with respect to alesion within a patient. A detailed description of such a motorizedbiopsy needle positioner, i.e. a stereotactic guidance system, is givenin U.S. Pat. No. 5,240,011, issued on Aug. 31, 1993, to Michael Assa,which is here incorporated herein by reference. The suspect lesion 59within the tissue to be sampled is targeted according to theinstructions provided with the stereotactic guidance system. Thestereotactic guidance system will enable an operator to advance thepoint 58 until it is adjacent the specific lesion region 59 to besampled, as illustrated in FIG. 2.

[0059] Once the point 58 is adjacent to the specific lesion region to besampled, fine tuning of the location of the point 59 within the tissuesample is preferably accomplished by actuating the linear actuator 47 tothereby advance and rest the hollow outer piercing needle 20 along itsaxis (the actuator 47 may, however, be used for rapid piercing as well).While the linear actuator 47 illustrated in FIG. 1, which uses apotential energy device (spring), is preferred, any of a variety ofdevices capable of inducing linear motion may be employed, includingsolenoids, pneumatic cylinders, or potential energy devices such assprings, motors, or the like. In operation of the preferred embodiment,the cocking lever 54 is pulled proximally against the fixed lever 55 tocompress the spring and cock the carriage assembly 50 in its proximalposition, as shown in FIG. 2. Then, when the needle 20 is positionedoutside the lesion, as illustrated in FIG. 2, the pierce button 56 isdepressed, releasing the carriage housing 50 so that the :springuncoils, forcing it rapidly in the direction of the arrow A (FIG. 3),such that the point 58 of the needle pierces the lesion 59.Alternatively, this procedure could be automated, using a needle controlunit to send signals to the linear actuator, which, in tun, wouldadvance and retract the hollow outer piercing needle 20 along its axis.

[0060] Now with particular reference to FIGS. 8-13, as seen in FIG. 8,the needle 20 is preferably advanced into the lesion 59 with the innercutter 22 in its fully advanced position to close off the tissuereceiving port 28, thus preventing snagging and tearing of the tissuedig slow linear movement of the needle 20. After the hollow outerpiercing needle 20 has been positioned at the precise location withinthe lesion 59 at which it is desired to obtain a tissue sample, a vacuumsource is actuated to apply a vacuum to the vacuum connection 32 in thetissue cassette housing 24 through the vacuum tube 34 (FIG. 1) as thecutter is retracted proximally (FIGS. 9 and 10). As a result, a regionof low pressure is generated within the hollow outer piercing needle 20in the vicinity of the tissue receiving port 28, and through the vacuumlumen 35. This facilitates the prolapse of tissue immediately adjacentto the tissue receiving port 28 into the interior of the hollow outerpiercing needle 20.

[0061] Once the tissue is fully prolapsed into the tissue receivingport, as shown in FIG. 10, the prolapsed tissue sample 60 is severedfrom the main tissue mass by the advancement of the cannular innercutter 22 (FIG. 11). The advancement of the inner cutter 22 is achievedby advancing the slide knob 44 attached to the pinion housing 42, thusadvancing the inner cutter 22 along its axis within the hollow outerpiercing needle 20 past the tissue receiving port 28, to thereby severthe prolapsed tissue sample from the main tissue mass. After beingsevered from the tissue mass, the tissue sample is packed into the innercutter as it moves forward against the needle pin 61 and rests insidethe inner cutter 22. The inner cutter 22, containing the tissue sample60, is then withdrawn by retracting the slide knob 44 (FIG. 12). Thetissue sample is held in the inner cutter 22 as it is withdrawnproximally toward the tissue cassette housing 24 by friction with theinner walls of the cannula. Suction created by the vacuum source canalso be used to retain the sample.

[0062] As the inner cutter 22 is withdrawn through the tissue cassettehousing 24, the tissue sample 60 is deposited into the tissue cassette26 by means of the tubular knock-out pin 36, the distal end of whichstops the tissue sample within one of the tissue containment chambers 62(FIG. 1), as is more fully described in the related application Ser. No.08/217,246. Once the tissue cassette 26 is filled with tissue samples,it may be removed form the tissue cassette housing 24 and transported toa laboratory for analysis, without the necessity of handling thesamples. If additional samples are desired, a new tissue cassette 26 maybe immediately inserted into the tissue cassette housing 24 and thecollection of samples may continue.

[0063] Referring now to FIG. 4, the needle assembly 18 of FIG. 1 isillustrated in greater detail. Significantly, the preferred embodimentof the needle assembly comprises a two-piece body, including the hollowouter piercing needle 20, with its inner cutter 22 and knock-out pin 36,and the tissue cassette housing 24. The frame of the tissue cassettehousing 24 (excluding the cassette 26) is preferably molded from asingle piece of plastic. If clear plastic is used, an additionaladvantage is the resultant ability to view the collected tissuespecimens in the cassette, which is located in a cassette port P in thehousing 24 during operation of the device. Magnification of the specimenis obtained by molding the top surface of the housing 24 to be convex,while the inner surface is substantially flat. The preferred one-pieceplastic cassette housing 24 includes a shaft potion 63, which provides aconduit for holding the cutter 22 and the knockout pin 36, and theproximal end portion 52, which in tun is adapted to be mounted on a post64 within the housing 14 (FIG. 1), forming a part of the carriageassembly 50. This portion of the cassette housing thus provides thesupport for the entire cantilevered needle assembly 18.

[0064] Yet another advantageous feature of the preferred needle assembly18 is the thumbwheel 30. The needle 20 is glued or otherwise securelyattached to the thumbwheel, which is then snapped into the housing 24.O-rings 65 fluidly seal the interface between the housing 24 and thethumbwheel 30, in order to preserve the vacuum between the port 32 andthe vacuum lumen 35 while simultaneously permitting rotation of thethumbwheel relative to the fixed housing 24. Because of this inventivefeature, the vacuum may be communicated to the needle 20 from the vacuumport 32 in the housing 24 no matter what the orientation of the needleis, without the problem sometimes encountered in prior embodimentswherein the vacuum tube 34 wraps about the housing 24 as it rotates withthe needle 20. The ability to keep the cassette housing 24 stationarysolves this hose problem.

[0065] FIGS. 14-17 illustrate a procedure enabled by the thumbwheel 30,whereby four tissue samples 60 may be acquired from four differentangular positions and deposited in the sample cassette 26 withoutremoving the hollow outer piercing needle 20 and the tissue receivingport 28 from the lesion 59. Furthermore, the integrity of each samplemay be preserved and a record of the location from which each of thefour samples is acquired may be created by storing the samples inindividual sample containment chambers 62 (FIG. 1). FIG. 14 is across-sectional view along lines 14-14 of FIG. 10, which illustratespreparations for the taking of a first sample 60 (FIG. 11) with theneedle 20 and associated vacuum lumen 35 angularly oriented so that thetissue receiving port is in an upright position within the lesion 59.FIG. 15 is a cross-sectional view along lines 15-15 of FIG. 12, whereinthe needle 20 is angularly oriented in the same position as in FIG. 14,after the tissue sample has been removed. The void 66 represents thelocation from which the sample was taken. FIG. 16 shows the needleassembly as illustrated in FIGS. 14 and 15, but where the thumbwheel 30(FIG. 4) has been used to rotate the needle 20 approximately 90 degreescounterclockwise. A second sample is to be taken from this angularlocation.

[0066] Finally, FIG. 17 is yet another similar view, wherein the needle20 has been rotated by the thumbwheel 30 approximately 300 degreescounterclockwise from the original orientation shown in FIGS. 14 and 15(it should, however, be noted that the invention permits samples to betaken from any angular orientation between 0 and 360 degrees). A samplehas already been taken from this orientation, as well as from the 180degree orientation, so that the void 66 now extends entirely about theneedle assembly and four tissue samples have been removed.

[0067] Now with reference to FIGS. 18 and 19, a modified embodiment of aportion of the needle assembly 18 of FIGS. 1, 4, and 5 is illustrated,wherein like elements are designated with like reference numerals,followed by the letter a. This needle assembly embodiment may be used inconjunction with a vacuum which is drawn through the cutter lumen 23 a,and particularly in a procedure where the physician wishes to obtainonly a single sample and wants to retain the tissue sample in the tissuereceiving port 28 a for retrieval (i.e. a “single-core” procedure).

[0068] Attached to the proximal end of the needle point 58 a is a distaltip 66 of a tissue stop or wire assembly 67, which comprises a wire 68which is integral with and extends proximally of the tip 66. Theattachment of the point 58 a to the tip 66 is preferably made bybrazing, though other equivalent known attachment methods maybe used aswell. The wire 68 extends beneath the entire axial length of the tissuereceiving port 28 a. Proximally of the tissue receiving port 28 a, andnear the proximal end of the wire 68, is a corkscrew portion 69, whichhas a diameter or cross-sectional width just slightly less than theinternal diameter of the inner cutter 22 a, as illustrated in FIG. 19.

[0069] In operation, with the cutter 22 a withdrawn proximally from theregion of the tissue receiving port 28 a, the wire assembly 67 isstationary in the lumen of the hollow outer piercing needle 20 a. Withthe needle in position in the tissue to be sampled, a vacuum is drawnthrough the cutter lumen 23 a and the needle lumen, thereby prolapsingtissue into the tissue receiving bowl 28 a. A potential problem is thatsuch tissue will prolapse all the way to the bottom of the bowl at aproximal region of the bowl, thereby cutting off the vacuum distally ofthe blocking portion. Without the vacuum, the distal portion of the bowlmay not receive a full volume of prolapsed tissue, thereby causing thetissue sample, when cut, to be only a partial sample. However, the wire68 functions to hold the prolapsed tissue in an elevated position abovethe bottom of the bowl, thereby preventing blockage of the lumen. Thispermits the vacuum to be transmitted all the way to the tip 66 so that afull-volume sample is assured.

[0070] Once the prolapsed tissue sample has been received, and cut offby the inner cutter 22 a, the corkscrew portion 69 functions to preventthe sample from being sucked or pulled out of the bowl 28 a duringwithdrawal of the a cutter. Then, after the needle is withdrawn from thepatient's body and the cutter 22 a is withdrawn from the bowl 28 a, thetissue sample remains in the bowl and may be retrieved directly from thebowl by the physician or an assistant.

[0071] In one preferred embodiment, the inner diameter of the hollowouter piercing needle 20 a was 0.014 inches, and the inner diameter ofthe inner cutter 22 a was 0.063 inches. The diameter of the wire 68 was0.014 inches, and the diameter or cross-sectional width of the corkscrewportion 69 was 0.060 inches. Of course, many other dimensions may beutilized as well. Additionally, while a corkscrew configuration ispreferred, many other configurations may be employed, as long as theyfunction to prevent proximal migration of the tissue sample, especiallyduring withdrawal of the cutter. For example, a simple kink in the wiremay be used, instead.

[0072] Now with particular reference to FIGS. 5 and 6, the distalportion of the needle assembly illustrated in FIGS. 1 and 4 is shown inperspective and in cross-section, respectively. Two particular featuresnot previously discussed are of note. First, in this particularembodiment, two preferably round vacuum ports 70 communicate between thetissue receiving port 28 and the vacuum lumen 35. The distal port 70 islocated distally of the tissue receiving port opening, so that it liesjust proximally of the point 58 and beneath overhang portion 71 of theneedle 20. In the preferred embodiment, it has a diameter ofapproximately 0.042 inches. The proximal port 70, on the other hand issignificantly smaller, preferably about one-half the diameter of thelarger port (approximately 0.020 inches), and lies directly beneath thetissue receiving port 28.

[0073] The second feature of note is related to how the needle point isground for sharpening. As illustrated in FIG. 5, it is preferred thatthe point be ground to form a plurality of facets 72 (preferably three)wherein no two facets axially intersect within the circumferential arcdefined by the tissue receiving port 28. Thus, the needle point 58defines a relatively flat surface on its upper side, as illustrated.This is advantageous in that the flat top surface 72 lifts the tissueupwardly and thereby assists its entry into the tissue receiving port28. On the other hand, if two of the facets 72 axially intersect withinthe arc defined by the tissue receiving port, the tissue often tends tosplit, potentially degrading the sample quality.

[0074] Referring now to FIG. 20, a modified embodiment of the needleassembly 18 illustrated in FIG. 6 is shown, wherein like elements aredesignated by like reference numerals, followed by the letter b. Theprimary difference between this embodiment and that of FIG. 6 is theemployment of a greater number of vacuum ports 70 b, preferably eight,between the vacuum lumen 35 b and the tissue receiving port 28 b. Inthis embodiment, preferably each of the ports 70 b is round and has adiameter of approximately 0.042 inches. Also, in this embodiment all ofthe ports are located beneath the opening of the tissue receiving port,as illustrated. None lie beneath the overhang portion 71 b.

[0075] The reason for the two different vacuum port configurations inFIGS. 6 and 20 is that each has advantages over the other when samplingcertain types of tissue. For example, in relatively fatty tissue, theeight hole embodiment illustrated in FIG. 20 may have a greater tendencyto clog. Clogging sometimes occurs when numerous samples are being takenbecause, as tissue is received into the tissue receiving port, thevacuum drawn through the vacuum ports 70 b tends to draw tissue past theports and into the vacuum lumen 35 b. Then, when the cutter 22 badvances to sever the tissue sample, small pieces of tissue within thevacuum ports fall into the vacuum lumen 35 b. Over many sampling cycles,the tissue buildup in the vacuum lumen 35 b partially blocks the vacuumto the distal ports, causing an uneven and diminished overall vacuumpressure and thereby reducing the quality of the tissue samples beingobtained. The two-port embodiment illustrated in FIG. 6 avoids thisproblem, because the single small port subject to contact with thetissue sample prolapsing into the tissue receiving port is so small thateven if tissue does fall into the vacuum lumen from this port, it doesnot build into a mass sufficient to cause a blockage. The port, on theother hand, is protected by the overhang 71 from contact with thetissue, so no tissue can become caught in the port to create clogging.

[0076] When relatively hard tissue is being sampled, in containing, theeight-port embodiment shown in FIG. 20 may be preferable. This isbecause hard tissue is less pliable, and therefore generally requires amore evenly distributed vacuum pressure to draw it fully into thetissue, receiving port. Obviously, the higher number of evenly spacedports in the FIG. 20 embodiment will provide this necessary drawingpressure. Furthermore, hard tissue is much less likely to actually bedrawn into the vacuum ports 70 b, so clogging is not a likely issue.

[0077]FIG. 21 illustrates a further modified embodiment of the needleassembly 18 illustrated in FIG. 6, wherein like elements are designatedby like reference numerals, followed by the letter c. The differencebetween the FIGS. 6, 20 and 21 embodiments is that in FIG. 21, thevacuum ports 70 c are arranged at an angle α with respect to thetransverse axis 80 of the needle assembly 18 c. Additionally, the sidewalls 82 of the tissue receiving port 28 c are preferably arranged atsubstantially the same angle α. In the preferred embodiment, the angle αis approximately 15-75 degrees. This angled orientation is advantageousbecause it permits the cutter 22 c (not shown in FIG. 21) to traversethe vacuum ports 70 c and side walls 82 of the tissue receiving port 28c more easily and minimizes damage to the cutter blade due tointerfering contact with these edges.

[0078] Yet another modified embodiment of the needle assembly embodimentillustrated in FIG. 6 is shown in FIG. 22. In this embodiment, likeelements are designated by like reference numerals, followed by theletter d.

[0079] The FIG. 22 embodiment is designed to assist in solving theclogging problem discussed with respect to the FIGS. 6 and 20embodiments and sometimes encountered during the process of collecting anumber of tissue samples from a patient during a single procedure. Aspreviously discussed, the problem is that bits of tissue, blood, andother biological debris will, over time, become detached from the tissuesamples being collected and become lodged in the tissue receiving port28 d, vacuum ports 70 d, or in one of the lumens 23 d or 35 d. Since thevacuum ports 70 d are relatively small, the problem of clogging thoseports is most acute, as the resultant reduced vacuum in the tissuereceiving port 28 d may cause the collection of partial tissue samples.Consequently, as illustrated in FIG. 22, a flush port 84 may be locatedbetween the vacuum lumen 35 d and the piercing needle lumen, similar tovacuum ports 70 d but located distally of the closed (most advanced)position of the cut 22 d . Then, when the cutter 22 d is in the closedposition, as illustrated, a pressurized saline solution may be permittedto flow through the cutter lumen 23 d into the needle lumen distally ofthe cutter, then through the flush port 84 as shown by the arrow 86, andfinally returned to its source through the vacuum lumen 35 d. Thisprocedure clears any accumulated debris and thus helps to ensure thatthe tissue samples are as complete as possible. A safety featureprevents saline from being injected through the system when the cutteris not in a fully closed position; i.e. completely blocking the tissuereceiving port 28 d.

[0080] As illustrated in FIG. 23, a problem sometimes encountered duringoperation of the biopsy device 10 (FIG. 1) is that the tissue sample 60being pulled into the tissue receiving port or bowl 28 may have atendency to bind as the relatively large cross-section of tissue isnecked down into the space between the rotating cutter 22 and the needle20. This problem is worsened because of the possible rotation of thecutter 22 relative to the stationary needle 20. In FIG. 24, a solutionto this problem is illustrated, wherein the cutter 22 e is modified tocomprise a relatively short blade portion 90, and a non-rotating sleeve92, preferably comprising a polyamide or a similar low-friction materialor coating, surrounds the remainder of the cutter and translates axiallywith it. The sleeve thus acts as an anti-tissue wrapping bearing,thereby helping to prevent tissue binding, and as a bearing to thecutter.

[0081]FIG. 25 illustrates a known prior art single-use biopsy device asdisclosed in U.S. Pat. No. 4,699,154 and Re. 34,056, both previouslyincorporated herein by reference. It should be noted that thisembodiment is merely representative of many different types of suchdevices currently or potentially available, any of which would besuitably used in conjunction with the inventive embodiments. However,the illustrated embodiment is illustrative and will serve as a goodpoint of reference.

[0082] In the device 94, a needle assembly 96 comprises a hollow outercutting cannula or needle 98 and an inner piercing needle 100. Theneedles 98 and 100 are pointed at their distal end, and the inner needle100 is also provided with a tissue receiving notch 102 at its distal endfor receiving the tissue sample. At their proximal ends, the needles 98and 100 are provided with heads 104 and 106, respectively, for mountingwithin the housing 108 of the sampling device. A front slide 110 and arear slide 112 are slidably provided along the axial direction of thehousing 108. Each slide 110 and 112, respectively, is actuated by atleast one spring 114 and 116, respectively, biasing the respective slidein a distal direction. The spring 114 acts between a stop 118 providedon the slide 110 and a fixed transverse wall (not shown) in the housing108. The spring 116 acts between a stop on the slide 112 and the rearend wall 120 of the housing 108. In the housing 108, there are twoparallel slide bars or guide rods 122, 124 on which the slides. 110, 112run.

[0083] The front slide 110 may be retained in a proximally withdrawnposition by means of a hook provided on a tongue member 126 protrudingfrom the slide, the tongue member engaging the bottom edge of theaforementioned transverse wall (not shown). The rear slide 112 may in acorresponding way be hooked and retained in a withdrawn position bymeans of a hook 128 protruding from the slide, which in turn engages aspringy hook member 130 at the rear wall 120 of the housing.

[0084] The tissue sampling device 94 is loaded and released in thefollowing manner. In the unloaded initial position, the slides 110, 112are each biased distally (toward the left) by the springs 114, 116,respectively. To load the device, the needle assembly 96, in which theinner needle 100 is freely slidable in the hollow outer cannula 98, ismoved proximally (to the right) and placed in the correct position inthe housing 108, so that the needle heads are engaged into the slides110, 112, which are configured to receive them, such that each needlehead 104, 106 follows the movements of the slides 110, 112,respectively.

[0085] Thus, when the needle assembly 96 has been placed in the device,the device is energized in that the slides 110, 112 are movedsimultaneously to their latched positions, whereby the springs 114, 116are compressed and would act to return the slides 110, 112 to theirinitial position if released from the latching hooks 126, 128, and 130.

[0086] When the needle assembly 96 has been positioned at the desiredtissue location, the sampling is carried out by pressing a releasebutton 132, whereby the engagement between the hooks 128 and 130 isinterrupted. Because of the biased spring 116, the slide 112 togetherwith the inner needle 100 is thus pushed distally toward the left to itsinitial position. For a short period of time, the slide 110, togetherwith the outer cannula 98, is still retained in its energized position.Thus, the inner piercing needle 100 protrudes from the outer cannula 98,thereby exposing the notch 102. Immediately after having reached itsinitial position, however, the slide 112 impacts and abuts the hookspring (tongue member) 126, and interrupts the engagement of the hookwith the transverse wall (not shown), whereby the spring 114 also pushesback the slide 110 distally to its initial position. Consequently, theouter cannula 98 again is pushed over the side facing notch 102 in theinner needle 100, thereby severing the tissue sample that has prolapsedinto the notch. Thereafter the needle assembly 96 is withdrawn from thetissue and removed from the sampling device, following which the sampleis analyzed.

[0087] While such a device works fairly well for its intended purposes,as discussed in the Background of the Invention, there are a number ofproblems inherent in their operation. Most significantly, there is nopositive means for engaging the tissue sample within the notch 102,particularly since no source of vacuum is available, as in theembodiments of FIGS. 1-24, to assist in collection of the tissue.Consequently, several inventive embodiments including mechanicalelements for capturing the issue are disclosed herein, each of whichdramatically improve the quality and quantity of the tissue samplescollected, on a consistent basis.

[0088] Referring now to FIGS. 26-28, a modified embodiment of the needleassembly 96. of FIG. 25 is illustrated, wherein like elements aredesignated by like reference numerals, followed by an a. In thisembodiment, in their initial position, as shown in FIG. 26, with bothsprings energized, the inner needle 100 a is retracted within the outercannula 98 a, and cutter leaflets 134 are in a closed position on thedistal end of the needle 98 a. Preferably, there are two, four, or sixcutter leaflets 134, which in the closed position come together to forma piercing cone. Of course, however, any number of leaflets may beemployed within the scope of the invention.

[0089]FIG. 27 illustrates the intermediate position immediately afterthe release button 132 (FIG. 25) has been activated. At this juncture,the spring 116 propels the inner needle 100 a distally, forcing theleaflets 134 open. The sharpened distal edges 136 of the needle 100 abegin to cut tissue, which is contained within the distal end portion ofthe needle 100 a. Then, upon release of the spring 114, the outercannula 98 a is propelled distally, as shown in FIG. 28, causing theleaflets 134 to snap closed to sever and contain the tissue sample 138.

[0090] It should be noted that this embodiment, while useful as amodification to the FIG. 25 device, may also be employed in the FIG. 1device. In this instance, the inner needle 100 a comprises a rotatingcutter, which translates back and forth as previously described.

[0091]FIGS. 29 and 30 illustrate a second modified embodiment of theneedle assembly in the FIG. 25 device. Again, like elements aredesignated by like reference numerals, followed by a b. In thisembodiment, the inner needle 100 b has been modified to include an“alligator” tip 140, which includes jaws 142, 144 and teeth 146. Whenthe spring 116 is released, the inner needle 100 b shoots distally andcaptures tissue in the opening 148 within the jaws 142, 144. Then, whenthe spring 114 is released, the outer cannula 98 b shoots distally,severing tissue along the sides of the tissue sample opening 148 as itmoves distally, and also forcing the jaws 142, 144 shut, so that they“bite off” the end of the tissue sample 138 b, as illustrated in FIG.30. This embodiment also may be adapted for use with the device of FIG.1, if desired.

[0092] Finally, FIGS. 3,1-34 illustrate a third modified embodiment ofthe needle; assembly in the FIG. 25 device. In this embodiment, likeelements are designated by like reference numerals, followed by a c.Like the FIG. 29 embodiment, the inner needle or “grabber” 100 c hasbeen modified, this time to include a plurality of hooked extractors 150extending from its distal end. The outer cannula 98 c includes asharpened cutter point 152. In operation, initially the grabber 100 c isacted into the cutter 98 c while the device is in its energized state,the point 152 being used to pierce the body wall 154 as the device isguided to the desired tissue sample 138 c (FIG. 32). Then, asillustrated in FIG. 33, the grabber 100 c is shot distally by means ofthe release of spring 116. As it travels distally, the hooked extractors150 become extended and latch onto the tissue sample 138 c. Then, oncethe second spring 114 is released, the cutter 98 c shoots distally,collapsing the hooked extractors 150 and severing the tissue sample,which is received into the lumen of the cutter 98 c.

[0093] This embodiment, as well, may be adapted for use with the deviceillustrated in FIG. 1. Furthermore, while four exactors 150 are shown,in actuality any desired number may be employed, as long as they may befully retracted within the cutter 98 c.

[0094] While this invention has been described with respect to variousspecific examples and embodiments, it is to be understood that theinvention is not limited thereto and that it can be variously practicedwithin the scope of the following claims.

What is claimed is:
 1. A biopsy instrument comprising: a housing; and aneedle assembly, said needle assembly comprising: a tubular piercingmember having a distal pointed end, and a laterally positioned tissuereceiving port proximate to said distal pointed end which opens into atissue sample chamber, wherein said tubular piercing member is rotatablyattached to said housing and held in an axially fixed position within atissue mass; a cannular cutting member adapted to coact with saidtubular piercing member to cut a tissue sample from the tissue mass suchthat the tissue sample can be transported to a proximate end of saidtubular piercing member by the cutting member as it is withdrawnproximally along said tubular piercing member; and an elongate knock-outpin disposed coaxially within said tubular piercing member and saidcannular cutting member and being adapted to dislodge said tissue samplefrom the cutting member as predetermined location as the cutting memberis withdrawn.
 2. A biopsy instrument as recited in claim 1, wherein saidknock-out pin has an effective diameter of at least 0.030 inches.
 3. Aibiopsy instrument as recited in claim 1, wherein said knock-out pin hasan effective diameter of approximately 0.045 inches.
 4. A biopsyinstrument as recited in claim 1, wherein the ratio of the effectivediameter of said knock-out pin to the internal diameter of said cannularcutter is at least approximately one-half.
 5. A biopsy instrument asrecited in claim 1, wherein said tubular piercing member comprises anelongate outer piercing needle and said cannular cutting membercomprises an elongate inner cannula disposed coaxially and slidablywithin said elongate outer piercing needle, said elongate inner cannulahaving a sharpened distal end for cutting a portion of tissue protrudinginto said elongate outer piercing needle tissue receiving port when saidelongate inner cannula slides past said port, thereby depositing theportion of cut tissue within said elongate inner cannula proximal tosaid sharpened distal end.
 6. A biopsy instrument as recited in claim 5,wherein said needle assembly further comprises a tissue cassettehousing, said housing including means interconnecting said tissuecassette housing and the hollow outer piercing needle to permit rotationof said outer needle without rotating said tissue cassette housing.
 7. Abiopsy instrument as recited in claim 6, wherein said interconnectingmeans comprises a thumbwheel.
 8. A biopsy instrument as recited in claim5, wherein said tissue cassette housing is fabricated molded plastic. 9.A biopsy instrument as recited in claim 8, wherein said plastic istransparent, in order to permit viewing of tissue samples containedtherein.
 10. A biopsy instrument as recited in claim 5, said needleassembly further comprising a vacuum lumen disposed beneath said outerpiercing needle and at least one fluid communication port between saidvacuum lumen and said tissue sample chamber for communicating a vacuumpressure from said vacuum lumen to said tissue sample chamber.
 11. Abiopsy instrument as recited in claim 10, wherein said at least onefluid communication port comprises a plurality of holes of substantiallyequal size, all of which are disposed directly beneath said tissuereceiving port.
 12. A biopsy instrument as recited in claim 10, whereinsaid at least one fluid communication port comprises a first relativelysmall hole disposed directly beneath said tissue receiving port and asecond relatively large hole disposed distally of said tissue receivingport so that it is shielded by an overhang comprising a portion of theouter cylindrical wall of the hollow outer piercing needle distally ofthe tissue receiving port.
 13. A biopsy instrument as recited in claim10, said needle assembly having a transverse axis and said at least onefluid communication port comprising a plurality of slots oriented at anangle α with respect to said transverse axis.
 14. A biopsy instrument asrecited in claim 13, wherein the transverse edges of said tissuereceiving port are oriented at said angle α with respect to saidtransverse axis.
 15. A biopsy instrument as recited in claim 14, whereinsaid angle α is within a range of 15-75 degrees.
 16. A biopsy instrumentas recited in claim 10, wherein said inner cannula may be advanceddistally a sufficient distance to completely close off said tissuereceiving port, said at least one fluid communication port comprising aport disposed distally of the distal end of the inner cannula when theinner cannula is in its fully advanced position, said port being adaptedfor use in flushing the needle assembly of excess material usingpressurized fluid.
 17. A biopsy instrument as recited in claim 1,wherein said needle assembly further comprises a non-rotatable bearingsleeve disposed about said cutting member.
 18. A biopsy instrument,comprising: an elongate hollow outer piercing needle having a lumen, asharpened distal end for piercing tissue, and a lateral opening locatedproximal to said sharpened distal end for receiving a portion of atissue mass positioned adjacent to said lateral opening; an elongateinner cutting cannula having a lumen and being disposed coaxially andslidable within said elongate outer piercing needle, said elongate innercannula having a sharpened distal end for cutting the portion of tissueprotruding into said elongate outer piercing needle lateral opening whensaid elongate inner cannula slides distally past said lateral opening,thereby depositing the portion of cut tissue within said elongate innercannula proximal to said sharpened distal end; a vacuum generator forgenerating a vacuum pressure which fluidly communicates with saidlateral opening through said inner cannula lumen; and a tissue stopdevice disposed in the lumen of said inner cannula and having astructure disposed proximally of said lateral opening which is adaptedto sufficiently obstruct said lumen so that a tissue sample drawn intothe lateral opening by said vacuum pressure and severed by the cuttingcannula is prevented from migrating proximally through the cuttingcannula lumen.
 19. A biopsy instrument as recited in claim 18, whereinsaid tissue stop device comprises a linear wire disposed along saidinner cannula lumen from the distal end thereof, the proximal end of thewire being configured to comprise said obstruction structure.
 20. Abiopsy instrument as recited in claim 19, wherein said obstructionstructure comprises a corkscrew position of said wire, thecross-sectional width of the corkscrew portion being just slightlysmaller than the internal diameter of said cutter lumen.
 21. A biopsyinstrument as recited in claim 19, wherein the distal end of said wirecomprises a tip which is fixedly attached to the distal end of thehollow outer piercing needle.
 22. A biopsy instrument, comprising: anouter hollow cannula having a distal end portion which comprises aplurality of leaflets, said leaflets each having a proximal end which ishinged to the outer cannula wall and a distal end, the leaflets beingbiased to pivot about their hinges to a closed position wherein thedistal ends of the leaflets contact one another; and an inner hollowcannula; wherein at least one of said cannulas is slidable relative tothe other cannula so that first the inner cannula may be extendeddistally with respect to the outer cannula to force said leaflets to anopen position and to cut and contain a tissue sample, and then the outercannula may be extended distally with respect to the inner cannulasufficiently so that the leaflets clear the inner cannula and snapclosed about their hinges, thereby serving said tissue sample andcontaining it within the inner cannula.
 23. A biopsy instrument,comprising: an outer hollow cannula having a sharpened distal endportion; and an inner hollow cannula having a distal portion which isbiased to expand radially at its distal end; wherein at least one ofsaid cannulas is slidable relative to the other cannula so that firstthe inner cannula may be extended distally with respect to the outercannula such that said inner cannula distal portion expands radially tocaputre a tissue sample, and then the outer cannula may be extendeddistally with respect to the inner cannula sufficiently so that thedistal end portion of the inner cannula is forced by the outer cannulato close about and sever the tissue sample, thereby containing thesample within the inner cannula
 24. A biopsy instrument as recited inclaim 23, wherein the distal portion of the inner cannula comprises analligator tip having a pair of hinged jaws which are biased to expandradially.
 25. A biopsy instrument as recited in claim 23, wherein thedistal portion of the inner cannula comprises a plurality of hookedextractors.
 26. A method of flushing debris from a biopsy instrumentcomprising an elongate outer piercing needle having a laterallypositioned tissue receiving port which opens into a tissue samplechamber in a lumen of the outer piercing needle, and an elongate innercutting cannula having an axial lumen, a sharpened distal end and beingdisposed coaxially and slidably within said elongate outer piercingneedle, said inner cannula being capable of advancement distally to aposition wherein the tissue receiving port is completely closed off,said needle assembly comprising a vacuum lumen disposed beneath saidtissue receiving port and further comprising at least one fluidcommunication port disposed distally of the distal end of the elongateinner cannula when the inner cannula is in its fully advanced position,said method comprising the steps of: a) advancing the inner cannula sothat is extends distally sufficiently to completely close off the tissuereceiving port; and b) injecting a pressurized fluid through one of saidinner cannula and said vacuum lumens, so that the fluid flows throughthe fluid communication port and into the other one of said two lumens,from which the fluid returns to its source, thereby flushing accumulateddebris from the biopsy instrument.